GU0601 - Larval Recruitment Survey - Leg I & II

March 10 - April 7, 2006

*GU0601 - Larval Recruitment Survey - Leg I & II*
March 10 *- April 7, 2006*

On March 10th, the Gordon Gunter departed Pascagoula and headed south to Key West FL, to load scientists and equipment for the GU0601 project. We then continued south to our working grounds along the Yucatan Peninsula to survey the ichthyoplankton and physical oceanography of the Quintana Roo, Mexico coast. The project was a collaboration between the National Oceanographic and Atmospheric Administration (NOAA) and El Colegio de La Frontera Sur (ECOSUR) in Chetumal, Mexico.

The emphasis was on the coastal areas of Sian Ka’an and Bancho Chinchorro (see maps below). These areas are established marine protected areas along the Mesoamerican reef in the Yucatan Peninsula, Mexico. According to the scientists, "Prior and ongoing work identified gaps in our knowledge about spawning aggregations, larval fish distributions, and oceanographic features. The goal was to map larval fish distributions in relation to identified spawning aggregation sites, identify oceanographic features, and use this information to model larval transport in the study area."

According to the experts, reef fish populations are part of one of the most complex ecosystems in the marine environment. They are also the most heavily exploited part of the ecosystem and have been pushed to extremely low levels throughout South Florida and the wider Caribbean (Roberts, 1997, Leis 2002). Despite the importance of these populations, relatively little is known about most stages of their life cycles. Important information such as adult spawning behavior, location, and depth of spawning aggregations and recruitment is mostly unknown. Less is known about the status of these fish populations in the western Caribbean along the Meso-American reef system (Vasquez-Yeomans and Richards, 1999; Vasquez-Yeomans et al., 1998), though stocks there are generally thought to have suffered less exploitation (Sosa-Codero et al. 2002).

The area we covered on this cruise is shown below (Click on photos to enlarge)

Track lines and stations on Leg I
Track line and stations on Leg II

"Two broad questions drive this research" says Dr. John Lamkin, the Chief Scientist for this cruise. "First, what is the level of larval dispersal and recruitment connectivity within and amongst the Mesoamerican reef, the Dry Tortugas, and the Florida Keys marine reserves? And second, is there evidence of self-recruitment within these marine reserves?"

To answer these questions, several methods were employed . The photos and descriptions below demonstrate the various operations during the cruise (Click on photos to enlarge):

The physical data consisted of continuous sea surface temperature, salinity, and chlorophyll fluorescence data collected via shipboard flow-through system, continuous upper 800 m current velocity data collected by a shipboard Acoustic Doppler Current Profiler (ADCP) system, and profiles of temperature, salinity, dissolved oxygen, and chlorophyll fluorescence collected by a lowered conductivity-temperature depth (CTD) system (see below). The CTD was also equipped with a lowered ADCP instrument for profiling velocity throughout the water column. Expendable bathythermographs (XBTs) were used between CTD stations to increase the horizontal resolution of the temperature field.
Water column profile, as deep as 1700 meters, were taken with the CTD rosette. Water samples were taken with the Niskin bottles (grey bottles) on the rosette. The bottles were sent down in the 'open' position (photos #1 & 2) and triggered to close at different depths, thus capturing water from different levels in the water column. The CTD unit (Current, Temperature & Depth), seen closely in photo #3, sent real time data on the depth, temperature (for salinity calculations) and current. The data was closely monitored and recorded by scientists in the lab (photo #5).	1. Preparing to deploy - bottles in 'open' position	2. CTD deployment
3. CDT unit	4. CTD retrieval - bottles 'closed'	5. watching the CTD on the computer
"Preliminary results of the physical data collection have identified the location and strength of the major currents of the region," says Dr. Elizabeth Johns, the head of the physical oceanography team onboard. "Maps of isotherm depths and surface properties have been generated and compared with satellite images of sea surface temperature, sea surface height, and sea surface ocean color. The cruise data will provide valuable ground-truthing information for the remotely sensed images."

The physical data consisted of continuous sea surface temperature, salinity, and chlorophyll fluorescence data collected via shipboard flow-through system, continuous upper 800 m current velocity data collected by a shipboard Acoustic Doppler Current Profiler (ADCP) system, and profiles of temperature, salinity, dissolved oxygen, and chlorophyll fluorescence collected by a lowered conductivity-temperature depth (CTD) system (see below). The CTD was also equipped with a lowered ADCP instrument for profiling velocity throughout the water column. Expendable bathythermographs (XBTs) were used between CTD stations to increase the horizontal resolution of the temperature field.

Water column profile, as deep as 1700 meters, were taken with the CTD rosette. Water samples were taken with the Niskin bottles (grey bottles) on the rosette. The bottles were sent down in the 'open' position (photos #1 & 2) and triggered to close at different depths, thus capturing water from different levels in the water column.

The CTD unit (Current, Temperature & Depth), seen closely in photo #3, sent real time data on the depth, temperature (for salinity calculations) and current. The data was closely monitored and recorded by scientists in the lab (photo #5).

1. Preparing to deploy - bottles in 'open' position

2. CTD deployment

3. CDT unit

4. CTD retrieval - bottles 'closed'

5. watching the CTD on the computer

"Preliminary results of the physical data collection have identified the location and strength of the major currents of the region," says Dr. Elizabeth Johns, the head of the physical oceanography team onboard. "Maps of isotherm depths and surface properties have been generated and compared with satellite images of sea surface temperature, sea surface height, and sea surface ocean color. The cruise data will provide valuable ground-truthing information for the remotely sensed images."

1. MOCNESS-1 frame and nets on deck	2. MOCNESS-1 deployment	Biological samples of the water column were taken with the MOCNESS-1 nets and light traps (see below). The MOCNESS-1 frame, holding 5 nets (photo #1), was lowered to the water with the bottom net in 'open' position (photo # 2). It was then lowered to depths over 2000 meters while being towed behind the ship at a speed of about 1.5 to 2 kts. When the 1st net was triggered to close at the bottom depth, the 2nd net opened. The 5th net was triggered, upon return, at the surface (photo # 3). In this manner, fish larvae was collected at 5 different levels of the water column.
3. MOCNESS-1 at the surface	4. MOCNESS-1 retrieval	LT Gilardo monitoring and triggering MOCNESS-1
The species collected in the water column by the MOCNESS were compared to those collected with the light traps (see below) and use the oceanographic data to help explain their distribution. All of this information, when put together, can best explain the supply of fishes to different areas and whether areas are linked as sources and destinations of larvae. This information is needed in order to design effective conservation strategies.

1. MOCNESS-1 frame and nets on deck

2. MOCNESS-1 deployment

Biological samples of the water column were taken with the MOCNESS-1 nets and light traps (see below). The MOCNESS-1 frame, holding 5 nets (photo #1), was lowered to the water with the bottom net in 'open' position (photo # 2). It was then lowered to depths over 2000 meters while being towed behind the ship at a speed of about 1.5 to 2 kts. When the 1st net was triggered to close at the bottom depth, the 2nd net opened. The 5th net was triggered, upon return, at the surface (photo # 3). In this manner, fish larvae was collected at 5 different levels of the water column.

3. MOCNESS-1 at the surface

4. MOCNESS-1 retrieval

LT Gilardo monitoring and triggering MOCNESS-1

The species collected in the water column by the MOCNESS were compared to those collected with the light traps (see below) and use the oceanographic data to help explain their distribution. All of this information, when put together, can best explain the supply of fishes to different areas and whether areas are linked as sources and destinations of larvae. This information is needed in order to design effective conservation strategies.

The another method of collecting biological samples was by deploying light traps near Banco Chinchorro reef. Per scientists Dave Jones and Dr. Monica Lara, the designers of the light traps: "We are conducting some specialized sampling of the late stages of fish larvae. These fishes are the ones that are nearing the time when they settle into their juvenile or adult habitat. The late stages of many species are attracted by light and so we are using special traps which have a timed light emission to gather samples near Chinchorro Reef. The light traps were designed and constructed at the NOAA Fisheries Service Lab in Miami, FL."
LTJG Davis, Dr. Lara and Sci Jones prepare to board the small boat and ferry out to the reef	Dr. Monica Lara exchanging light traps	A couple of tiger grouper larvae (Epinephelus tigris) collected during this cruise

The inport for this cruise was Majahual, Mexico. This lovely fishing village on the Yucatan Peninsula, just north of the border between Mexico and Belize, has become a prime cruise ship destination. About 500 ships frequent this port, known in the cruising circles as Costa Maya, every year.
We tied up at the cruise ship terminal. Some went diving off of Majahual. Others took a road trip to visit the ruins at Chachoben, and take a dip at Lake Bacalar. Yet some, just kicked back at the beach bars and restaurants of Majahual. Good time was had by all, as seen in the photos below (Click on photos to enlarge):

Gordon Gunter at the pier in Majahual	Same pier, a day later	Majahual beach	Majahual town
l-r: ENS Perry, 3AE Baumman and ENS Zalewski	Underwater scenery	More underwater scenery	Divers returning to Majahual by the local taxi
Visiting the Mayan ruins at Chachoben	Close look at the pyramid	Another pyramid of different design	Group photo
Laka Bacalar	The restaurant at Lake Bacalar	Cervesa (beer) break....	Majahaul beach bar

Photo credits on this webpage go to scientists and crew onboard the NOAA ship GORDON GUNTER during the cruise. All photos property of NOAA.

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•  Updated:September 20, 2006